Combine the frozen cheese tortellini, sliced Italian sausage, and fresh spinach in the crockpot. Pour in the Italian-style diced tomatoes and low-fat chicken broth, then add the cream cheese.

Gently stir the mixture to ensure all ingredients are well incorporated and the cream cheese blends with the liquids, then cover the crockpot.

Set the crockpot to low cooking setting and let it simmer for about 4 hours, keeping an eye for bubbling around edges.

Stir occasionally every hour to incorporate the melting cream cheese and allow flavors to meld.

Check that the sausage is fully cooked, ladle into bowls, and garnish with parmesan cheese and crushed red pepper flakes if desired.